BATS are unique because they are the only true
flying mammals. Bats wings are thin membranes of skin stretched from fore to
hind legs, and from hind legs to tail. This skin is bare or thinly furred.
Most Missouri bats are members of the evening bat family. They are generally inactive during the brighter hours of the day, preferring evening, night and early morning for their feeding flights. When not in flight, they rest in the dark seclusion of natural places such as caves, hollow trees and rock crevices. They also may occupy vacant buildings, church steeples, attics,spaces between walls, and belfries. Bats can enter places of refuge through very small openings or cracks as narrow as three-eighths of an inch.
All Missouri bats eat insects which are captured in flight. During the winter when food is in short supply, bats must either hibernate or migrate to warmer climates. Two species--the silver-haired and hoary bat--migrate south during the fall and return in the spring. The red and hoary bat are solitary and usually roost in trees. The other species form colonies. They spend the colder months in hibernation, frequently in caves where they hang in clusters waiting for spring, warm weather and a new supply of insect food. These colonial bats use caves, barns and other buildings as summer roosts.
The Indiana bat and gray bat have been classified as endangered species. These bats are colonial hibernators, usually roosting in caves. It is unlikely that these species affect the general public, since they are seldom in conflict with man's interests. However, spelunkers have been known to disturb colonies to the point that the bats abandoned their cave.
The little brown bat and big brown bat are the species most commonly found in buildings. Female bats occupy nursery colonies in late spring or early summer when they give birth to young. Within a month, the young make feeding flights, but the colony may remain until fall dispersal to hibernation caves. Few bats overwinter in buildings.
Control
Because of their insectivorous habits, bats are beneficial. Bats do not destroy property by gnawing or chewing. They occupy a special place among mammals because they can fly. They do not compete with other mammals for food or shelter. For these reasons, bats should not be needlessly destroyed.
The incidence of bats transmitting disease to man is low, but if such a situation occurred, it would suggest a need for control. Bat bites can be dangerous. As a precaution against exposure to disease, do not handle live bats. In case of bat bites, wash the area immediately with hot, soapy water and promptly notify a physician. If possible, capture the bat without damaging the head, place it in a jar or plastic bag and refrigerate. Health authorities may want it for a rabies test.
Mechanical methods. By accident, an individual bat may enter a home through open doors, chimneys or windows unprotected by screens. When this occurs, chase the bat out open doors or windows with a broom; or wait until the bat settles, then cover it with a can or jar so you can slip a cover under the opening of the container without touching the bat. Wearing gloves during this procedure is recommended. Release the bat outdoors.
When a colony of bats occupies a building, the accumulation of droppings and
the odor of bat urine are objectionable. Bat droppings are the size of mouse
droppings, crumble easily, usually are shiny black, irregular in shape and contain
insect fragments; they accumulate below the walls and rafters where bats roost.
Bat squeaks and the rustling noise they make as they enter or leave the roosts
may also be bothersome to the building's occupants.
The only permanent method of preventing these roosts is to bat-proof the building. Do this by locating and blocking all entrances through which bats gain access. Entryways may be located by watching outside the building during the last half-hour of daylight and noting the points from which the bats emerge. Note such places as attic louvers, jointure of chimney and house, and gable ends. After the entryways are located, plan the needed repairs; nail loose siding, caulk crevices, replace missing moulding or trim, and cover larger openings with 1/4-inch mesh hardware cloth. Keep in mind that sealing the openings must be done after the bats leave the roost at twilight or after they disperse in the fall. If the openings are blocked during daylight roosting hours, the bats will be sealed inside the building.
Bright lights may disperse certain bat roosts. Where it is possible to illuminate entire roost areas in structures, the bats may be dispersed before bat-proofing. Illumination for several days may cause the bats to seek alternative dark areas for daytime roosting. Bat roosts in sites such as wall or floor partitions are impossible to illuminate for this method of dispersal.
Pesticides. Naphthalene flakes (moth crystals) are legally registered as a bat repellent. If the bats are in a confined space such as between walls or restricted attic areas, the odor of naphthalene flakes may discourage bat roosts.
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Missouri Department of Conservation, University of Missouri, U.S. Fish & Wildlife Service
Content revision: 20030627
